Shedding light on cashmere goat hair follicle biology: from morphology analyses to transcriptomic landascape

Melatonin's Role in Hair Follicle Growth and Development: A Cashmere Goat Perspective

Hair follicles, unique skin appendages, undergo cyclic phases (anagen, catagen, telogen) governed by melatonin and associated molecular pathways. Melatonin, synthesized in the pineal gland, skin, and gut, orchestrates these cycles through antioxidant activity and signaling cascades (e.g., Wnt, BMP). This review examines melatonin's biosynthesis across tissues, its regulation of cashmere growth patterns, and its interplay with non-coding RNAs and the gut-skin axis. Recent advances highlight melatonin's dual role in enhancing antioxidant capacity (via Keap1-Nrf2) and modulating gene expression (e.g., Wnt10b, CTNNB1) to promote hair follicle proliferation. By integrating multi-omics insights, we construct a molecular network of melatonin's regulatory mechanisms, offering strategies to improve cashmere yield and quality while advancing therapies for human alopecia.

Deciphering the molecular drivers for cashmere/pashmina fiber production in goats: a comprehensive review

Cashmere, also known as pashmina, is derived from the secondary hair follicles of Cashmere/Changthangi goats. Renowned as the world's most luxurious natural fiber, it holds significant economic value in the textile industry. This comprehensive review enhances our understanding of the complex biological processes governing cashmere/pashmina fiber development and quality, enabling advancements in selective breeding and fiber enhancement strategies. The review specifically examines the molecular determinants influencing fiber development, with an emphasis on keratins (KRTs) and keratin-associated proteins (KRTAPs). It also explores the roles of key molecular pathways, including Wnt, Notch, BMP, NF-kappa B, VEGF, cAMP, PI3K-Akt, ECM, cell adhesion, Hedgehog, MAPK, Ras, JAK-STAT, TGF-β, mTOR, melanogenesis, FoxO, Hippo, and Rap1 signaling. Understanding these intricate molecular cascades provides valuable insights into the mechanisms orchestrating hair follicle growth, further advancing the biology of this coveted natural fiber. Expanding multi-omics approaches will enhance breeding precision and deepen our understanding of molecular pathways influencing cashmere production. Future research should address critical gaps, such as the impact of environmental factors, epigenetic modifications, and functional studies of genetic variants. Collaboration among breeders, researchers, and policymakers is essential for translating genomic advancements into practical applications. Such efforts can promote sustainable practices, conserve biodiversity, and ensure the long-term viability of high-quality cashmere production. Aligning genetic insights with conservation strategies will support the sustainable growth of the cashmere industry while preserving its economic and ecological value.

A comparative proteomic-based study identifies essential factors involved in hair follicle growth in inner Mongolia cashmere goats

Renowned for its invaluable undercoat, the cashmere goat is well known. The growth of cashmere fibre initiates when the relatively inactive telogen stage transitions to the anagen stage, which involves active proliferation. However, the molecular mechanisms responsible for this process are still unclear. Here, SWATH mass spectrometry (MS), a comparative proteomic analysis, was conducted to examine the proteomic alterations in Inner Mongolia cashmere goat skin samples at two different developmental stages (anagen and telogen). In total, 2414 proteins were detected, with 631 proteins showing differential regulation (503 upregulated proteins and 128 downregulated proteins). Bioinformatic analysis revealed that these proteins, which are differentially regulated, play crucial roles in the pathways associated with metabolism and fatty acids according to the GO and KEGG analyses. Furthermore, interactome analysis revealed that differentially regulated keratins have a crucial impact. The localization of KRT25, KRT71, and KRT82 using immunohistochemistry revealed that these proteins were expressed in the secondary hair follicles of cashmere goat skin. The keratin family plays an irreplaceable and important role in the process of hair follicle growth.

Integrative transcriptomic and metabolomic analyses reveal the role of melatonin in promoting secondary hair follicle development in cashmere goats

BACKGROUND

Melatonin improves the production performance of animal furs, particularly in promoting wool and cashmere growth. Although most studies of melatonin enhancing cashmere growth have focused primarily on gene and phenotype levels, its impact on metabolites has not received attention. To investigate the influence of melatonin on metabolites, genes, gene‒metabolite interactions, and associated signaling pathways in secondary hair follicles (SHFs), we performed multiomics analyses of skin and blood samples collected 30 days after sustained melatonin release.

RESULTS

The results demonstrated that two melatonin interventions during SHF anagen in cashmere goats induce the early growth of SHFs, increase the active secondary follicle density (ASFD), and improve cashmere yield and quality. Transcriptomic analysis revealed 509 differentially expressed genes (DEGs), including key genes such as KRTs and KRTAPs, and genes associated with the WNT signaling pathway (LEF1, WNT3/4, and FZD3/5), suggesting their critical roles in melatonin-mediated SHF development. Metabolomic analysis revealed 842 metabolites in the skin samples and 1,162 in the blood samples. Among these, 177 differentially regulated metabolites (DRMs) in the skin were significantly enriched in pathways such as alpha-linolenic acid metabolism, glyoxylate and dicarboxylate metabolism, the citrate cycle (TCA cycle), and several amino acid metabolic pathways. Similarly, 122 DRMs in the blood were enriched in pathways related to protein digestion and absorption, central carbon metabolism in cancer, and aminoacyl-tRNA biosynthesis. Finally, the integrative analysis revealed partially coenriched metabolic pathways and relationships between DEGs and DRMs.

CONCLUSIONS

In summary, by integrating transcriptomics and metabolomics, this study provides novel insights into the role of melatonin in promoting SHF development. Furthermore, these findings establish a theoretical foundation for the broader application of melatonin-based technologies to promote cashmere growth.

Telomere-to-telomere genome assembly of a male goat reveals variants associated with cashmere traits

A complete goat (Capra hircus) reference genome enhances analyses of genetic variation, thus providing insights into domestication and selection in goats and related species. Here, we assemble a telomere-to-telomere (T2T) gap-free genome (2.86 Gb) from a cashmere goat (T2T-goat1.0), including a Y chromosome of 20.96 Mb. With a base accuracy of >99.999%, T2T-goat1.0 corrects numerous genome-wide structural and base errors in previous assemblies and adds 288.5 Mb of previously unresolved regions and 446 newly assembled genes to the reference genome. We sequence the genomes of five representative goat breeds for PacBio reads, and use T2T-goat1.0 as a reference to identify a total of 63,417 structural variations (SVs) with up to 4711 (7.42%) in the previously unresolved regions. T2T-goat1.0 was applied in population analyses of global wild and domestic goats, which revealed 32,419 SVs and 25,397,794 SNPs, including 870 SVs and 545,026 SNPs in the previously unresolved regions. Also, our analyses reveal a set of selective variants and genes associated with domestication (e.g., NKG2D and ABCC4) and cashmere traits (e.g., ABCC4 and ASIP).

The molecular anatomy of cashmere goat hair follicle during cytodifferentiation stage

BACKGROUND

Cashmere, named as "soft gold", derives from the secondary hair follicles (SHFs) of cashmere goat which is vital to Northwest China's economy. The cytodifferentiation stage (E120), mirroring the complete hair follicle (HF) structure of adult goats and marking a critical phase in SHF development. Therefore, this study aims to enhance the understanding of SHF development and its impact on fiber quality, informing breeding strategies.

RESULTS

From the scRNA-seq data analysis, the intricate processes and transcriptional dynamics of inner layer cell differentiation of HFs were unveiled in this study. we identified nine cell populations during cytodifferentiation and key structures such as the hair shaft and inner root sheath. And we discovered three main inner layer lineages and seven subpopulations, clarifying their roles in specialization and signaling. Pseudotime mapping analysis showed cell evolution from early stage to mature stages marked by unique gene expressions, and the intermediate stage on the differentiation of each lineage was revealed. The identification and spatial localization of specific transcription factors, such as GATA3, LEF1 and PRDM1, as well as keratin genes highlight regulatory pathways involved in HF development, which was further validated by immunofluorescence. These findings suggested the potential strategies to improve fiber quality, and the discovery of diverse cell types and their developmental molecular mechanisms, particularly in this species-specific context, offered a nuanced view of the regulatory mechanisms driving HF development in cashmere goats.

CONCLUSION

Overall, these findings provide a systematic molecular atlas of skin, defining three major branches and cell states of inner layer cells of HF, and determining how the branch-specific transcription factors, keratins, and signals coordinate HF morphogenesis during cytodifferentiation stage. This research not only advances skin tissue research in goats but also holds broader implications for the understanding of HF regeneration and development across various species.

Developmental Mapping of Hair Follicles in the Embryonic Stages of Cashmere Goats Using Proteomic and Metabolomic Construction

The hair follicle (HF) is the fundamental unit for fleece and cashmere production in cashmere goats and is crucial in determining cashmere yield and quality. The mechanisms regulating HF development in cashmere goats during the embryonic period remain unclear. Growing evidence suggests that HF development involves complex developmental stages and critical events, and identifying the underlying factors can improve our understanding of HF development. In this study, samples were collected from embryonic day 75 (E75) to E125, the major HF developmental stages. The embryonic HFs of cashmere goats were subjected to proteomic and metabolomic analyses, which revealed dynamic changes in the key factors and signalling pathways controlling HF development at the protein and metabolic levels. Gene ontology and the Kyoto Encyclopaedia of Genes and Genomes were used to functionally annotate 1784 significantly differentially expressed proteins and 454 significantly differentially expressed metabolites enriched in different HF developmental stages. A joint analysis revealed that the oxytocin signalling pathway plays a sustained role in embryonic HF development by activating the MAPK and Ca2+ signalling pathways, and a related regulatory network map was constructed. This study provides a global perspective on the mechanism of HF development in cashmere goats and enriches our understanding of embryonic HF development.

Downregulated INHBB in endometrial tissue of recurrent implantation failure patients impeded decidualization through the ADCY1/cAMP signalling pathway

PURPOSE

This study aims to identify the mechanism of Inhibin Subunit Beta B (INHBB), a member of the transforming growth factor-β (TGF-β) family involved in the regulation of human endometrial stromal cells (HESCs) decidualization in recurrent implantation failure (RIF).

METHODS

RNA-seq was conducted to identify the differentially expressed genes in the endometria from control and RIF patients. RT-qPCR, WB, and immunohistochemistry were performed to analyse the expression levels of INHBB in endometrium and decidualised HESCs. RT-qPCR and immunofluorescence were used to detect changes in the decidual marker genes and cytoskeleton after knockdown INHBB. Then, RNA-seq was used to dig out the mechanism of INHBB regulating decidualization. The cAMP analogue (forskolin) and si-INHBB were used to investigate the involvement of INHBB in the cAMP signalling pathway. The correlation of INHBB and ADCY expression was analysed by Pearson's correlation analysis.

RESULTS

Our results showed significantly reduced expression of INHBB in endometrial stromal cells of women with RIF. In addition, INHBB was increased in the endometrium of the secretory phase and significantly induced in in-vitro decidualization of HESCs. Notably, with RNA-seq and siRNA-mediated knockdown approaches, we demonstrated that the INHBB-ADCY1-mediated cAMP signalling pathway regulates the reduction of decidualization. We found a positive association between the expression of INHBB and ADCY1 in endometria with RIF (R2 = 0.3785, P = 0.0005).

CONCLUSIONS

The decline of INHBB in HESCs suppressed ADCY1-induced cAMP production and cAMP-mediated signalling, which attenuated decidualization in RIF patients, indicating that INHBB is an essential component in the decidualization process.

A Kaleidoscope of Keratin Gene Expression and the Mosaic of Its Regulatory Mechanisms

Keratins are a family of intermediate filament-forming proteins highly specific to epithelial cells. A combination of expressed keratin genes is a defining property of the epithelium belonging to a certain type, organ/tissue, cell differentiation potential, and at normal or pathological conditions. In a variety of processes such as differentiation and maturation, as well as during acute or chronic injury and malignant transformation, keratin expression undergoes switching: an initial keratin profile changes accordingly to changed cell functions and location within a tissue as well as other parameters of cellular phenotype and physiology. Tight control of keratin expression implies the presence of complex regulatory landscapes within the keratin gene loci. Here, we highlight patterns of keratin expression in different biological conditions and summarize disparate data on mechanisms controlling keratin expression at the level of genomic regulatory elements, transcription factors (TFs), and chromatin spatial structure.

Effects of exogenous melatonin on expressional differences of immune-related genes in cashmere goats

The interplay between melatonin and immune system is well recognized in humans. The true integration of research on cashmere goat is still far from clear, especially for cashmere goat maintained in wool and cashmere growth. In this study, we applied various approaches to identify the complex regulated network between the immune-related genes and transcription factors (TFs) and to explore the relationship between melatonin and gene expression in cashmere goats. In total, 1,599 and 1756 immune-related genes were found in the blood and skin of cashmere goats, respectively, and 24 differentially expressed immune-related GO terms were highly expressed in blood after melatonin implantation. We studied the melatonin-dependent networks between the TFs and immune-related genes in cashmere goat. The 3 major regulatory networks were interconnected through TFs. The TFs, such as PHF5A, REXO4, STRAP, JUNB, GATAD2A, ZNF710, and VDR, were also expressed in the blood and skin tissue of cashmere goat. In addition, most genes in these networks, such as VDR, JUNB, and Trib3, were involved in WNT pathway, which is related to cashmere wool growth regulation. On the network basis, we developed a knockout mouse model to identify the network interaction. We observed that 8 high-sulfur protein genes, 12 keratin (KRT) genes, and 19 keratin associated protein (KRTAP) genes related to the growth of cashmere wool were almost not expressed in Trib3^−/− rat skin. Our results suggested that the expression of genes related to wool and cashmere growth may be regulated by the interaction network between genes affected by melatonin and immune-related genes. In summary, we outlined some particularly promising ways for future research on immune-related genes of cashmere goats and the role of melatonin in wool and cashmere growth.

Integrated analysis of lncRNAs and mRNAs by RNA-Seq in secondary hair follicle development and cycling (anagen, catagen and telogen) of Jiangnan cashmere goat (Capra hircus)

BACKGROUND

Among the world's finest natural fiber composites is derived from the secondary hair follicles (SHFs) of cashmere goats yield one of the world's best natural fibres. Their development and cycling are characterized by photoperiodism with diverse, well-orchestrated stimulatory and inhibitory signals. Long non-coding RNA (lncRNAs) and mRNAs play important roles in hair follicle (HF) development. However, not many studies have explored their specific functions in cashmere development and cycling. This study detected mRNAs and lncRNAs with their candidate genes and related pathways in SHF development and cycling of cashmere goat. We utilized RNA sequencing (RNA-Seq) and bioinformatics analysis on lncRNA and mRNA expressions in goat hair follicles to discover candidate genes and metabolic pathways that could affect development and cycling (anagen, catagen, and telogen).

RESULTS

We identified 228 differentially expressed (DE) mRNAs and 256 DE lncRNA. For mRNAs, catagen and anagen had 16 upregulated and 35 downregulated DEGs, catagen and telogen had 18 upregulated and 9 downregulated DEGs and telogen and anagen had 52 upregulated and 98 downregulated DEGs. LncRNA witnessed 22 upregulated and 39 downregulated DEGs for catagen and anagen, 36 upregulated and 29 downregulated DEGs for catagen and telogen as well as 66 upregulated and 97 downregulated DEGs for telogen and anagen. Several key genes, including MSTRG.5451.2, MSTRG.45465.3, MSTRG.11609.2, CHST1, SH3BP4, CDKN1A, GAREM1, GSK-3β, DEFB103A KRTAP9-2, YAP1, S100A7A, FA2H, LOC102190037, LOC102179090, LOC102173866, KRT2, KRT39, FAM167A, FAT4 and EGFL6 were shown to be potentially important in hair follicle development and cycling. They were related to, WNT/β-catenin, mTORC1, ERK/MAPK, Hedgehog, TGFβ, NFkB/p38MAPK, caspase-1, and interleukin (IL)-1a signaling pathways.

CONCLUSION

This work adds to existing understanding of the regulation of HF development and cycling in cashmere goats via lncRNAs and mRNAs. It also serves as theoretical foundation for future SHF research in cashmere goats.

Whole blood transcriptome profiling identifies candidate genes associated with alopecia in male giant pandas (Ailuropoda melanoleuca)

Background

The giant panda (Ailuropoda melanoleuca) is a threatened species endemic to China. Alopecia, characterized by thinning and broken hair, mostly occurs in breeding males. Alopecia significantly affects the health and public image of the giant panda and the cause of alopecia is unclear.

Results

Here, we researched gene expression profiles of four alopecia giant pandas and seven healthy giant pandas. All pandas were approximately ten years old and their blood samples collected during the breeding season. A total of 458 up-regulated DEGs and 211 down-regulated DEGs were identified. KEGG pathway enrichment identified that upregulated genes were enriched in the Notch signaling pathway and downregulated genes were enriched in ribosome, oxidative phosphorylation, and thermogenesis pathways. We obtained 28 hair growth-related DEGs, and identified three hub genes NOTCH1, SMAD3, and TGFB1 in PPI analysis. Five hair growth-related signaling pathways were identified with abnormal expression, these were Notch, Wnt, TGF-β, Mapk, and PI3K-Akt. The overexpression of NOTCH1 delays inner root sheath differentiation and results in hair shaft abnormalities. The delayed hair regression was associated with a significant decrease in the expression levels of TGFB1.

Conclusions

Our data confirmed the abnormal expression of several hair-related genes and pathways and identified alopecia candidate genes in the giant panda. Results of this study provide theoretical basis for the establishment of prevention and treatment strategies for giant pandas with alopecia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08501-z.